Utilizing resonance inspection of in-service parts

ABSTRACT

Various embodiments relating to resonance inspections and in-service parts are disclosed. One protocol ( 150 ) includes conducting a resonance inspection of an in-service part ( 152 ). The frequency response of the in-service part may be compared with a resonance standard ( 154 ) for purposes of determining whether or not the in-service part is changing abnormally ( 156 ). An in-service part that is identified as changing abnormally may be characterized as being “rejected” ( 160 ). An in-service part that is no identified as changing abnormally may be characterized as being “accepted” ( 158 ).

CROSS-REFERENCE TO RELATED APPLICATIONS

This patent application is a continuation of U.S. patent applicationSer. No. 13/278,380 that is entitled “UTILIZING RESONANCE INSPECTION OFIN-SERVICE PARTS,” that was filed on Oct. 21, 2011, and also claimspriority to, pending U.S. Provisional Patent Application Ser. No.61/405,573 that is entitled “UTILIZING RESONANCE INSPECTION OFIN-SERVICE PARTS,” that was filed on Oct. 21, 2010, and the entiredisclosure of which is hereby incorporated by reference in its entiretyherein.

FIELD OF THE INVENTION

The present invention generally relates to the field of testing partsand, more particularly, to the field of resonance inspection of partsthat involves exciting a part at a number of different frequencies andobtaining the frequency response of the part to the various excitations.

BACKGROUND OF THE INVENTION

A variety of techniques have been developed in which parts may be tested“nondestructively,” meaning that the testing methodology enables defectsto be identified without causing damage to the part. Examples of suchnondestructive-testing methodologies include acoustic techniques,magnetic-particle techniques, liquid-penetrant techniques, radiographictechniques, eddy-current testing, and low-coherence interferometry,among others. There are various known advantages and disadvantages toeach of these categories of testing methodologies, which are accordinglyused in different environments.

Nondestructive-testing methods that use acoustic radiation generallyoperate in the ultrasonic range of the acoustic spectrum, and arevaluable for a number of reasons. Such techniques are sensitive, forexample, to both surface and subsurface discontinuities, enablingidentification of defects both within the bulk and near the surface of apart. The depth of penetration for defect detection is generallysuperior to many other nondestructive-testing methodologies, and thetechniques are highly accurate not only in determining the position of adefect, but also in estimating its size and shape.

SUMMARY

The present invention is generally directed to resonance inspections. Inat least certain instances, resonance inspection results from onein-service part are compared with resonance inspections results from oneor more other in-service parts. Any resonance inspection-basedcomparison between one part and at least one other part for purposes ofthe present invention is directed to comparing parts that are at leastfunctionally equivalent. “Functionally equivalent” includes where theparts are manufactured from common design specifications. However,“functionally equivalent” also encompasses the situation where parts aremanufactured from different design specifications, but which may be usedin the same end-use application. For instance, a given engine may allowturbine blades to be manufactured from either of a pair of designspecifications. Resonance inspection-based comparisons for purposes ofthe present invention may be made between turbine blades used by thenoted engine, but which are manufactured from the noted different designspecifications. Typically, the differences between parts that aresubject to a resonance inspection-based comparison for purposes of thepresent invention will not be of a radical nature (e.g., the parts willbe on the same class (e.g., turbine blades), the parts will be verysimilar dimensionally).

A first aspect of the present invention is embodied by a method ofevaluating in-service parts by resonance inspection. A resonanceinspection includes exciting a given part at a plurality of inputfrequencies and obtaining a frequency response of the part. A resonanceinspection is performed on a first in-service part for purposes of thefirst aspect. The frequency response from the resonance inspection ofthe first in-service part is compared with what may be characterized asa “resonance standard.” Generally, this resonance standard defines howthe first in-service part should normally change while in service. Thecomparison of the frequency response from the resonance inspection ofthe first in-service part to the resonance standard is utilized todetermine if the first in-service part is changing abnormally.

A number of feature refinements and additional features are applicableto the first aspect of the present invention. These feature refinementsand additional features may be used individually or in any combination.The following discussion is applicable to the first aspect, up to thestart of the discussion of a second aspect of the present invention.

The resonance standard, against which the frequency response from theresonance inspection of the first in-service part is compared, may bestored on a computer-readable storage medium. For instance, theresonance standard may be stored on a hard drive, disk drive, opticaldrive, flash drive, or the like, that is utilized by a computer that maybe utilized to make the comparison required by the first aspect. In anycase, the comparison of the frequency response from the resonanceinspection of the first in-service part with the resonance standard, aswell as the determination as to whether or not the first in-service partis changing abnormally, may utilize at least one processor (e.g., one ormore processors of any appropriate type, where multiple processors maybe integrated/implemented in any appropriate manner).

The resonance standard, against which the frequency response from theresonance inspection of the first in-service part is compared, may be ofany appropriate type and/or defined in any appropriate manner. Oneembodiment has this resonance standard including spectra (e.g., a“snapshot” of the frequency response of a part at one or more points intime) of at least one other in-service part (e.g., an in-service partother than the first in-service part). Another embodiment has thisresonance standard being in the form of a mathematical model (e.g.,resonance inspection results generated from software based uponprojections/predictions as to how a part should normally change overtime when in use or service).

The resonance standard associated with the first aspect may be directedto comparing how the first in-service part is changing relative to apopulation of in-service parts (e.g., in-service parts that arecomparable with the first in-service part in one or more respects,including where the in-service parts within the population and the firstin-service part are produced from or in accordance with commonspecifications). If the first in-service part is changing at leastgenerally in accordance with the population, the first in-service partmay be characterized as changing normally. Otherwise, the firstin-service part may be characterized as changing abnormally.

The resonance standard used by the first aspect may be based uponresonance inspection data from a population of in-service parts. In oneembodiment, the population of in-service parts does not include thefirst in-service part. In any case, the resonance standard may be in theform of one or more representative spectra (e.g., one spectra for eachof a plurality of in-service parts that are part of the population). Agiven representative spectra may also be in the form of an average ofspectra from each of the plurality of in-service parts that are includedwithin the noted population (or from a plurality of in-service partswithin the population). The resonance standard may also be in the formof spectra from a single member of the population.

Consider the case where a first assembly is defined by what may becharacterized as first assembly specifications. This first assembly mayinclude a first part. Although this first part could be required toconform with one set of first part specifications for purposes ofcomplying with the overall first assembly specifications (e.g., wherethe first in-service part and the population of in-service parts aredefined by and/or manufactured in accordance with commonspecifications), it may be such that first assembly specificationsallows this first part to conform with any one of a plurality ofdifferent first part specifications (e.g., the first assemblyspecifications could allow the first part to be in accordance witheither specifications #1 or specifications #2, where there is at leastone difference between specifications #1 and #2). As such, it may bethat the first in-service part is interchangeable (e.g., functionally)with the in-service parts in the population, but may actually vary inone or more respects from one or more in-service parts in thepopulation.

The resonance standard is subject to yet another characterization. Aplurality of first parts may be manufactured. Each of these first partsmay be put into service (e.g., used for the intended purpose and/or inan intended end-use application; after being released from productionfor use by a customer, end user, or the like). The first in-service partassociated with the first aspect may be one of these first parts. Afterthe plurality of first parts have been in service for a certain duration(e.g., measured in any appropriate manner, such as cycles of operation,operating time, a certain time period, or the like), a resonanceinspection is performed on each of a plurality of the first parts. Theresonance standard may be defined by the results of the resonanceinspection of at least some of the plurality of first parts, includingwhere the resonance standard is defined by the results of the resonanceinspection of one or more of the plurality of first parts other than thefirst in-service part.

The resonance standard used by the first aspect may include results froma plurality of spaced-in-time resonance inspections that were previouslyperformed on another in-service part that corresponds with the firstin-service part. “Corresponding with” includes where this secondin-service part and first in-service part each conform to predeterminedspecifications. It should be appreciated that these “predeterminedspecifications” may in fact allow the second in-service part and thefirst in-service part to vary in one or more respects, other thanaccording to a specified tolerance (e.g., the first and secondin-service part may be interchangeable for an end-use application, butthey may differ in one or more respects and other than by having adifferent value within a specified tolerance). In any case and in oneembodiment, this “second” in-service part is incorporated by what may becharacterized as a “fleet leader.” A “fleet leader” may be an end use ofthe second in-service part that experiences higher-than-normal usageover a certain period of time (e.g., an aircraft that has ahigher-than-average number of landings over a certain period of time).In another embodiment, this “second” in-service part is one that hasundergone accelerated life testing. “Accelerated life testing” may becharacterized as involving the acceleration of failures of a part forthe purpose of quantifying the life characteristics of the part atnormal use conditions.

“Usage information” (any parameter that characterizes the amount ofusage of a given in-service part, such as hours of operation, cycles ofoperation, or the like) may or may not be utilized for purposes ofdetermining whether the first in-service part is changing normally orabnormally in the case of the first aspect. For instance, the firstaspect may be configured so that the first in-service part ischaracterized as changing normally, even though the resonance inspectionresults of the first in-service part comply with the resonance standardat different numbers of cycles. That is, the first aspect may beconfigured to characterize the first in-service part as changingnormally if its resonance inspection results at the 5,000 cycle levelcomply with the resonance standard at the 10,000 cycle level.

The first aspect may be also configured so that the frequency responsefrom at least one resonance inspection of the first in-service part(e.g., the first resonance inspection that is undertaken after the firstin-service part has been put into service) must comply with acorresponding part of the resonance standard in terms of amount ofusage. For instance, the resonance inspection data from a resonanceinspection of the first in-service part at 5,000 cycles may be requiredto comply with the resonance inspection data from the resonance standardthat is also associated with 5,000 cycles). Thereafter, the first aspectmay be configured so that the first in-service part is characterized aschanging normally, even though the resonance inspection results of thefirst in-service part comply with the resonance standard at differentnumbers of cycles. That is, the first aspect may be configured tocharacterize the first in-service part as changing normally if itsresonance inspection data at 10,000 cycles complies with the resonancestandard at 15,000 cycles.

Another option is for the first aspect to be configured so that thefrequency response from at least one resonance inspection of the firstin-service part (e.g., the first resonance inspection that is undertakenafter the first in-service part has been put into service) must at alltimes comply with a corresponding part of the resonance standard interms of amount of usage. For instance, the resonance inspection datafrom a resonance inspection of the first in-service part at 5,000 cyclesmay be required to comply with the resonance inspection data from theresonance standard that is also associated with 5,000 cycles, theresonance inspection data from a resonance inspection of the firstin-service part at 10,000 cycles may be required to comply with theresonance inspection data from the resonance standard that is alsoassociated with 10,000 cycles, and so forth. Yet another option is forthe first aspect to be configured so as to not utilize any usageinformation for purposes of determining whether the first in-servicepart is changing normally (e.g., so long as the resonance inspectiondata on the first in-service part complies with any resonance inspectiondata of the resonance standard, the first in-service part may becharacterized as changing normally for purposes of the first aspect).

A second aspect of the present invention is embodied by a method ofevaluating in-service parts by resonance inspection. A resonanceinspection includes exciting a given part at a plurality of inputfrequencies and obtaining a frequency response of the part. For purposesof the second aspect, a resonance inspection is performed on a pluralityof in-service parts that collectively define what may be characterizedas a first part group. A first subset is selected from the first partgroup and is characterized or associated with being “normal.” Resultsfrom the resonance inspection of at least one in-service part from thefirst subset may be used to define a normal standard. A second subset isselected from the first part group and is characterized or associatedwith being “abnormal.” Results from the resonance inspection of at leastone in-service part from the second subset may be used to define anabnormal standard. Both the normal and abnormal standards may be storedon a computer-readable storage medium of what may be characterized as aresonance inspection tool or system.

A number of feature refinements and additional features are applicableto the second aspect of the present invention. These feature refinementsand additional features may be used individually or in any combination.The following discussion is applicable to the second aspect, up to thestart of the discussion of a third aspect of the present invention.Initially, the second aspect may be repeated any appropriate number oftimes (e.g., for a number of different first part groups; at a number ofdifferent points in time in relation to the same first part group). Theresonance inspection tool may include multiple normal standards,multiple abnormal standards or both. The normal standard may includeresonance inspection results from one or more resonance inspections ofone or more in-service parts from any first subset of any first partgroup, the abnormal standard may include resonance inspection resultsfrom one or more resonance inspections of one or more in-service partsfrom any second subset of any first part group, or both.

The selection that defines the first subset (e.g., “normal”) may bebased upon data other than results of the resonance inspection of eachof the plurality of in-service parts from which the first subset isdefined. In one embodiment, the selection for purposes of defining thefirst subset utilizes nondestructive testing, destructive testing, orboth. Similarly, the selection that defines the second subset (e.g.,“abnormal”) may be based upon data other than results of the resonanceinspection of each of the plurality of in-service parts from which thesecond subset is defined. In one embodiment, the selection for purposesof defining the second subset utilizes nondestructive testing,destructive testing, or both. One or more non-destructive testingtechniques may be used, one or more destructive techniques may be used,or both, in relation to the second aspect. Representative nondestructivetesting techniques that may be used in relation to the second aspectincludes without limitation visual inspection, microscopy, magneticparticle, penetrant, eddy current, x-ray, computed tomography, flashthermography, ultrasound, sonic infra-red, phased array, or the like.Representative destructive testing techniques that may be used inrelation to the second aspect includes without limitation fatiguetesting, static testing, thermal testing, metalography, sectioning,ablation, chemical reduction, or the like.

Using the results of the resonance inspection to define a normalstandard for purposes of the second aspect may entail defining at leastone relationship (e.g., a first relationship) in the spectra provided bythe resonance inspection of at least one in-service part that is withinthe first subset. Another embodiment is directed to using the results ofthe resonance inspection to define a normal standard for purposes of thesecond aspect, and more specifically defining at least one relationshipin the spectra provided by the resonance inspection of a plurality ofin-service parts that are each within the first subset. Similarly, usingthe results of the resonance inspection to define an abnormal standardfor purposes of the second aspect may entail defining at least onerelationship (e.g., a second relationship) in the spectra provided bythe resonance inspection of at least one in-service part that is withinthe second subset. Another embodiment is directed to using the resultsof the resonance inspection to define an abnormal standard for purposesof the second aspect, and more specifically defining at least onerelationship in the spectra provided by the resonance inspection of aplurality of in-service parts that are each within the second subset.

The resonance inspection tool or system may be used to assess anin-service part after the normal and abnormal standards have been storedin relation to the second aspect. The normal and abnormal standardsassociated with the second aspect may be characterized as collectivelydefining a “sort functionality” for the resonance inspection tool orsystem. Such a “sort functionality” may be directed to providing theresonance inspection tool or system with the ability to determinewhether an in-service part should be accepted or rejected after aresonance inspection has been conducted using the resonance inspectiontool or system (along with the normal and/or abnormal standards).

Consider the case where a resonance inspection of a first in-servicepart is conducted using the resonance inspection tool having the storednormal and abnormal standards from the second aspect. The results fromthis particular resonance inspection may be compared with at least oneof the normal standard and the abnormal standard. In one embodiment, thefirst in-service part is accepted by the resonance inspection tool ifthe results of its resonance inspection comply with the normal standard.In one embodiment, the first in-service part is rejected by theresonance inspection tool if the results of its resonance inspectionfail to comply with the normal standard. In yet another embodiment, thefirst in-service part is rejected by the resonance inspection tool ifthe results of its resonance inspection comply with the abnormalstandard. An in-service part could be rejected by the resonanceinspection tool if the results of the corresponding resonance inspectionfails to comply with the normal standard, complies with the abnormalstandard, or both.

The normal standard, the abnormal standard, or both, may includeresonance inspection data from the resonance inspection of one or morein-service parts. For instance, the normal standard could be acollection of a plurality of spectra (from a resonance inspection) forin-service parts that have been characterized as “normal,” the abnormalstandard could be a collection of a plurality of spectra (from aresonance inspection) for in-service parts that have been characterizedas “abnormal.” The “usage information” discussed above in relation tothe first aspect could be utilized by this second aspect as well. Assuch, the normal standard could include at least one spectra (from aresonance inspection) for an in-service part that has been characterizedas normal, and corresponding usage information may be stored in relationto each such spectra (e.g., the normal standard could include spectrafor a in-service part at 5,000 cycles, 10,000 cycles, 15,000 cycles, andso forth). Similarly, the abnormal standard could include at least onespectra (from a resonance inspection) for an in-service part that hasbeen characterized as abnormal, and corresponding usage information maybe stored in relation to each such spectra (e.g., the normal standardcould include spectra for an in-service part at 5,000 cycles, 10,000cycles, 15,000 cycles, and so forth).

A third aspect of the present invention is embodied by a method ofevaluating new production parts by resonance inspection. A resonanceinspection includes exciting a given part at a plurality of inputfrequencies and obtaining a frequency response of the part. For purposesof the third aspect, a resonance inspection is performed on a firstin-service part. A first manufacturing defect is identified in the firstin-service part. Data from the resonance inspection of the firstin-service part is selected and where this resonance inspection datacorresponds with the first manufacturing defect (e.g., the selectedresonance inspection data correlates with the first manufacturingdefect). A new production part sort functionality of a resonanceinspection tool is updated based upon this selection of data from thenoted resonance inspection.

A number of feature refinements and additional features are applicableto the third aspect of the present invention. These feature refinementsand additional features may be used individually or in any combination.The following discussion is applicable to the third aspect, up to thestart of the discussion of a fourth aspect of the present invention.Generally, the third aspect may be characterized as using the results ofa resonance inspection of an in-service part to adjust the sortfunctionality used by a resonance inspection tool to assess newproduction parts. In one embodiment: 1) prior to being updated inaccordance with the third aspect, the new production part sortfunctionality of the resonance inspection tool was configured toactually accept a new production part that has the first manufacturingdefect; and 2) after being updated in accordance with the third aspect,the new production part sort functionality of the resonance inspectiontool should be of a configuration that will reject a new production partthat has the first manufacturing defect.

The first manufacturing defect in the first in-service part may becomemore evident as the first in-service part is put into service. Data fromone or more resonance inspections of the first in-service part(including when the same was in the form of a new production part—priorto being released from production and/or put into service by a customer,end user, or the like) may be analyzed to determine how the newproduction part sort functionality of the resonance inspection toolshould be adapted so as to be able to identify the existence of thefirst manufacturing defect in a new production part. The resonanceinspection tool may then be configured to reject a new production parthaving such a first manufacturing defect.

The first manufacturing defect in the first in-service part may beidentified in any appropriate manner. In one embodiment, nondestructivetesting, destructive testing, or both may be used to originally identifythe first manufacturing defect. One or more nondestructive testingtechniques may be used, one or more destructive techniques may be used,or both, in relation to the third aspect. Those representativenondestructive and destructive testing techniques discussed above inrelation to the second aspect may be used by the third aspect as well.In any case and in one embodiment, after the first manufacturing defecthas been identified, resonance inspection results may be reviewed toidentify how the first manufacturing defect may be identified from theresonance inspection results.

A fourth aspect of the present invention is embodied by a method ofevaluating in-service parts by resonance inspection. A resonanceinspection includes exciting a given part at a plurality of inputfrequencies and obtaining a frequency response of the part. A resonanceinspection is performed on a first in-service part at a plurality ofdifferent times in its lifecycle (e.g., throughout the life of the firstin-service part). First resonance inspection data is monitored for anoccurrence of a first condition. This first condition is a predeterminedtime-rate-of-change in the first resonance inspection data over multipleresonance inspections. An end-of-life determination for the firstin-service part is based upon the identification of an occurrence of thefirst condition.

A number of feature refinements and additional features are applicableto the fourth aspect of the present invention. These feature refinementsand additional features may be used individually or in any combination.The following discussion is applicable to at least the fourth aspect.Generally, the fourth aspect may be characterized as being directed tobasing an end-of-life determination on a certain time-rate-of-change inat least part of the resonance inspection data from multiple and spacedin time resonance inspections of the first in-service part (e.g.,resonance inspections conducted on the first in-service part at 5,000cycles, 10,000 cycles, 15,000 cycles, and so forth).

The first in-service part may undergo resonance inspections on anyappropriate basis for purposes of the fourth aspect. For instance, aresonance inspection of the first in-service part may be conducted on ascheduled basis and based upon some type of usage information (e.g.,hours of operation; cycles of operation). For instance, the firstin-service part could be scheduled for a resonance inspection ever “x”cycles. The first in-service part could also be scheduled for aresonance inspection on what may be characterized as a “target cycle”basis. Each target cycle could be a range of cycles, a minimum number ofcycles, or the like. A resonance inspection could be recommended for thefirst in-service part when it has been operated for 4,000-6,000 cycles,another resonance inspection could be recommended for the firstin-service part when it has been operated for 9,000-11,000 cycles, andso forth. A resonance inspection could be recommended for the firstin-service part when it has been operated for at least 5,000 cycles,another resonance inspection could be recommended for the firstin-service part when it has been operated for at least 10,000 cycles,and so forth.

The first resonance inspection data used by the fourth aspect may bestored on a computer-readable storage medium. In one embodiment, themonitoring of the first resonance inspection data is performed by acomputer. A resonance inspection tool may monitor the first resonanceinspection data for an occurrence of a first condition.

The resonance inspection data that is acquired on the first in-servicepart may include the first resonance inspection data. In one embodiment,the first resonance inspection data is only part of the resonanceinspection data that is acquired from each resonance inspection of thefirst in-service part. The first resonance inspection data may also becharacterized as being based upon and/or derived from the resonanceinspection data acquired from each resonance inspection of the firstin-service part.

The first resonance inspection data may be in the form of a frequencyshift in the resonance inspection data acquired from multiple resonanceinspections of the first in-service part. The first resonance inspectiondata may be in the form of: 1) a relative shift of at least one peak inthe resonance inspection data acquired from multiple resonanceinspections of the first in-service part (e.g., a shift of a first peakin the resonance inspection data relative to a second peak in theresonance inspection data); 2) an absolute shift of at least one peak inthe resonance inspection data acquired from multiple resonanceinspections of the first in-service part (e.g., a shift of a first peakin the resonance inspection data); 3) an appearance of at least one peakin the resonance inspection data acquired from multiple resonanceinspections of the first in-service part; and 4) a disappearance of atleast one peak in the resonance inspection data acquired from multipleresonance inspections of the first in-service part.

The first resonance inspection data may be plotted. The predeterminedtime-rate-of-change associated with the fourth aspect may be in the formof a predetermined slope (e.g., rise over run) for the plot. Therefore,the first condition may occur when the noted plot exhibits at least acertain slope. In one embodiment, the noted plot is of a frequency shift(e.g., how a certain peak in resonance inspection data for the firstin-service parts shifts over time), where the y-axis may characterizethis shift in any appropriate manner (e.g., expressed as a percentagechange in the location of a peak from a previous-in-time resonanceinspection), and where the x-axis may characterize corresponding usageinformation in any appropriate manner (e.g., number of cycles). Considerthe case where Peak 1 is at a certain frequency at time t₀ (e.g., whenreleased from production). Peak 1 may be at a different frequency attime t₁ (e.g., at the time of the first resonance inspection), at yet adifferent frequency at time t₂ (e.g., at the time of the secondresonance inspection), and so forth. How Peak 1 is shifting may bequantified by the y-axis of the noted plot and for the associated time(where “time” may be expressed in any appropriate manner, such as inhours, cycles, or the like).

A number of feature refinements and additional features are separatelyapplicable to each of above-noted first, second, third, and fourthaspects of the present invention. These feature refinements andadditional features may be used individually or in any combination inrelation to each of the above-noted first, second, third, and fourthaspects. An “in-service part” in the context of the present inventionencompasses a part that has been used to at least some extent afterhaving been released by the manufacturer. An in-service part may be apart that has been put into use by a party other than the manufacturer(e.g., a customer or end user). Although an in-service part could beused autonomously, an in-service part may be incorporated by a largerassembly (e.g., a turbine blade in a jet engine).

A resonance inspection of a given part may utilize a first transducerthat excites or drives the part at multiple frequencies (e.g., bysweeping through a predetermined range of frequencies), along with atleast one other transducer that measures the frequency response of thispart to such excitations or drive frequencies (e.g., therebyencompassing using two “receiver” transducers). Any number offrequencies may be used to excite the part for the resonance inspection,and the excitation frequencies may be input to the part in anyappropriate pattern and for any appropriate duration. Another option isto use a single transducer for performing a resonance inspection. Inthis case, a transducer may drive a given part at a certain frequencyfor a certain amount of time, and thereafter this same transducer may beused to obtain the frequency response of this part (e.g., afterterminating the driving of the transducer at an input frequency). Thismay be repeated for multiple input or drive frequencies.

Any appropriate combination of excitation or drive frequencies may beused for a resonance inspection for purposes of the present invention.Each transducer that is used to perform a resonance inspection forpurposes of the present invention may be of any appropriate size, shape,configuration, and/or type, and will typically be in contact with thepart (including where one or more transducers support the part to atleast some extent). Although a resonance inspection for purposes of thepresent invention could be performed in situ (e.g., with the part in aninstalled condition or state, for instance on a turbine blade that ismounted within a jet engine), such a resonance inspection could beperformed on a part that has been removed from service (e.g., at a timewhen the part is in an uninstalled condition or state, for instance on aturbine blade that has been removed from a jet engine).

The various aspects of the present invention each may be implemented asa method and/or as an inspection system or tool. In the case of aninspection system or tool, an assessment module may be configured toexecute the assessments noted herein (e.g., such an assessment modulemay utilized logic that is configured to assess a particular part inaccordance with a defined protocol), where a given part may be excitedand the frequency response may be obtained in accordance with any one ormore of the configurations addressed herein.

Any feature of any other various aspects of the present invention thatis intended to be limited to a “singular” context or the like will beclearly set forth herein by terms such as “only,” “single,” “limitedto,” or the like. Merely introducing a feature in accordance withcommonly accepted antecedent basis practice does not limit thecorresponding feature to the singular (e.g., indicating that a resonanceinspection system utilizes “a frequency response transducer” alone doesnot mean that the resonance inspection system utilizes only a singlefrequency response transducer). Moreover, any failure to use phrasessuch as “at least one” also does not limit the corresponding feature tothe singular (e.g., indicating that a resonance inspection systemutilizes “a frequency response transducer” alone does not mean that theresonance inspection system utilizes only a single frequency responsetransducer). Use of the phrase “at least generally” or the like inrelation to a particular feature encompasses the correspondingcharacteristic and insubstantial variations thereof (e.g., indicatingthat a structure is at least generally cylindrical encompasses thestructure being cylindrical). Finally, a reference of a feature inconjunction with the phrase “in one embodiment” does not limit the useof the feature to a single embodiment.

BRIEF DESCRIPTION OF THE FIGURES

FIG. 1 is a block-diagram of one embodiment of a resonance inspectiontool.

FIG. 2 shows a simplified block diagram of the resonance inspection toolof FIG. 1.

FIG. 3 is a block-diagram of another embodiment of a resonanceinspection tool.

FIG. 4 presents various resonance inspection results of parts that maybe included in the library utilized by the resonance inspection tool ofFIG. 3.

FIG. 5 is one embodiment of a resonance inspection protocol that may beutilized by a resonance inspection tool.

FIG. 6 is one embodiment of an in-service part sort protocol that may beutilized by a resonance inspection tool.

FIG. 7 is one embodiment of an in-service part sort initializationprotocol that may be utilized by a resonance inspection tool.

FIG. 8 is one embodiment of an in-service part sort protocol that may beutilized by a resonance inspection tool, including in conjunction withthe sort initialization protocol of FIG. 7.

FIG. 9 is one embodiment of a new production part sort update protocolthat may be utilized by a resonance inspection tool.

FIG. 10 is another embodiment of an in-service part sort protocol thatmay be utilized by a resonance inspection tool.

FIG. 11 illustrates a time-rate-of-change of resonance inspectionresults that may be used by the in-service part sort protocol of FIG.10.

DETAILED DESCRIPTION

Various applications of resonance inspection (e.g., resonance ultrasoundspectroscopy; process compensated resonance testing) are addressedherein. Various principles that may relate to resonance inspection areaddressed in the following U.S. patents, the entire disclosures of whichare incorporated by reference in their entirety herein: U.S. Pat. Nos.5,408,880; 5,425,272; 5,495,763; 5,631,423; 5,641,905; 5,837,896;5,866,263; 5,952,576; 5,965,817; 5,992,234; and 6,199,431.

One embodiment of a resonance inspection tool or system (e.g., foraccommodating resonant ultrasound spectroscopy measurement with aplurality of sensors; for process compensated resonance testing) isillustrated in FIGS. 1 and 2, and is identified by reference numeral 5.The resonance inspection tool 5 includes a computer 10 that provides forcontrol of a synthesizer 12 and an analog to digital converter 11 foreach data input channel connected to each receiving or responsetransducer 22, 24 of the resonance inspection tool 5. Transducer 22 hasan output on line 31, while transducer 24 has an output on line 25.

Synthesizer 12 may have a frequency range from greater than 0 to 20 MHertz. Other frequency ranges may be appropriate. Synthesizer 12provides two outputs which are the frequency F1 at output 14 and asecond output which is the frequency F2 at line 16. In one embodiment,the frequency F2 is either F1 plus a constant frequency such as 1000Hertz for heterodyne operation of the receiver, or at F1 for homodyneoperation. A first transducer 18 (e.g., the input or driving transducer)is excited at a frequency F1 by synthesizer 12. Transducer 18 providesvibration (e.g., ultrasonic) to an object 20 to be tested via resonanceinspection.

The response of the object 20 is then received by two separate outputtransducers 22 and 24. The circuitry from the output transducer 22 andA/D converter 11 can be identical to circuitry between output transducer24 and A/D converter 11. For this reason, only the circuitry betweenoutput transducer 22 and A/D converter 11 will be discussed below. Thetimes one (.times.1) amplifier 26 is connected to the output transducer22, provides current for transformer 28, and has a feedback 27.

The output of transducer 22 is connected to a receiver 41 (FIG. 2).Receiver 41 is used for the purpose of providing amplification and noiserejection in the circuit between output transducer 22 and A/D converter11. The output A (line 40) is applied to the A/D converter 11 within thecomputer 10. The A/D converter 11 provides an A/D conversion for each oflines 40 and 42. The converted information is then entered into a filewhich consists of the measured frequency, the amplitude of A, theamplitude of B, the amplitude of A plus B, and the amplitude of A minusB. This file is then used for further analysis of the spectrum todetermine characteristics of a part 20 being tested.

The times one (.times.1) amplifier 26 provides feedback to an innercoaxial cable shield 30 which surround the lead from transducer 22 toamplifier 26. Shield 30 is another grounded shield which can also beused for noise suppression. The outer surrounding coaxial cable is notshown in FIG. 1. If lead 31 is short, the shield 30 may be omittedbecause capacitance will not be too large. The purpose of the innershield 30 is to provide a cancellation of capacitance of the lead 31.

The transformer 28 may be a 4:1 step-down transformer used for impedancematching to the input of amplifier 32. In this regard, it should benoted that the output impedance of amplifier 26 may be much lower thanthe output impedance of transducer 22. This provides for the power gainand the necessary feedback to shield 30. The amplifier 32 may have again factor of 100:1 or a 40 db gain. Other gain factors may beappropriate. The amplifier 26 may be a broad-band amplifier having aband pass on the order of 50 M Hertz.

Mixer 34 has an output signal (e.g., a 1 K Hertz signal) having amagnitude which is proportional to the magnitude of the frequency F1provided on line 14 from synthesizer 12. The function of the synthesizer12 is to provide a point-by-point multiplication of instantaneous valuesof inputs on lines 16 and 33. The mixer 34 also has many high frequencyoutput components which are of no interest. The high frequencycomponents are therefore filtered out by the low-band pass filter 38which is connected to mixer 34 by line 36. Filter 38 serves to clean-upthe signal from mixer 34 and provide a voltage on line 40 which is onlythe output signal at an amplitude which is proportional to the amplitudeof the output 31 of transducer 22.

Operation of the resonance inspection tool 5 will be briefly describedin relation to measurement steps performed by measurement of the outputof either transducer 22 or transducer 24 controlled by computer 10. Ameasurement cycle may be initiated, and provides initialization for thefrequency F and the desired frequency step. The frequency step may be 1Hertz or any other frequency selected for the measurement. Although aconstant frequency step may be utilized, the frequency step may bedetermined by any appropriate algorithm. In one embodiment, thefrequency step is determined by determining the start frequency and thestop frequency, and dividing the frequency difference by the number ofsteps desired for the measurement. In any case, the synthesizer 12 isconfigured to provide a plurality of input or drive frequencies totransducer 18.

Once a signal is picked up by the receiver (i.e., an output on line 33),a pause for ring delay there is a provided. The pause for ring delay maybe on the order of 30 milliseconds, although other ring delays can beused if the object under test 20 has resonances that are narrower than afew Hertz. The purpose of the pause is to give the object 20 anopportunity to reach its steady state magnitude in response to a steadyinput from transducer 18. The pause time is time after the frequency isapplied and before detection is initiated.

After the ring delay is complete, analog-to-digital converter 11provides an output that can be used by the data recording computer. Theoutput of the A/D conversion is then written to a file by the computer10 for the purpose of analysis of the data by another program. Datacomprising the unique signature or characterizing of the object 20 iswritten into file as it is created. Reading may be stopped when a readfrequency is present and step 66 stops the program. Once information isentered into file, subsequent processing can be used to generate asignature or characterize the object 20 such as the resonant magnitudes,the sum of resonant magnitudes, the difference resonant magnitudes, orother manipulations of the multiple channel multiple frequencymeasurement which is used to perform the unique signature of the object20. The magnitude of the outputs at each sensor location for eachresonance frequency may be compared.

Another embodiment of a resonance inspection tool or system isillustrated in FIG. 3 and is identified by reference numeral 100. Theresonance inspection tool 100 includes a signal generator 102 of anyappropriate type, at least one transducer of any appropriate type thatinterfaces with a part 120 (e.g. via physical contact) that is toundergo a resonance inspection (e.g., transducer 104), and a computer108. The computer 108 may include what may be characterized as anassessment module 110. Generally, the assessment module 110 may beconfigured to evaluate the results of a resonance inspection, forinstance for purposes of determining whether the part 120 should beaccepted or rejected by the resonance inspection tool 100, determiningwhether the part 120 is at an end-of-life state or condition, or thelike. A part 120 that is “accepted” by the resonance inspection tool 100may mean that the resonance inspection tool 100 has determined that thepart 120 may be put into service (e.g., utilized for its intendedpurpose(s) and/or used according to its design specifications). In oneembodiment, a part 120 that has been accepted by the resonanceinspection tool 100 means that the tool 100 has determined that the part120 is free of defects, is not in an end-of-life condition or state, isaging normally, or any combination thereof. A part 120 that is“rejected” by the resonance inspection tool 100 may mean that theresonance inspection tool 100 has determined that the part 120 shouldnot be put into service (e.g., should not be utilized for its intendedpurpose(s) and/or should no longer be used according to its designspecifications). In one embodiment, a part 120 that has been rejected bythe resonance inspection tool 100 means that the tool 100 has determinedthat the part 120 includes at least one defect, is at or near anend-of-life condition or state, is aging abnormally, or any combinationthereof.

A part 120 that is analyzed or assessed by the resonance inspection tool100 may be of any appropriate size, shape, configuration, type, and/orclass. For purposes of the resonance inspection tool 100, there could betwo part classes. One part class includes new production parts—newlymanufactured parts that have not yet been released from production(e.g., parts that have not been shipped for use by an end user orcustomer). New production parts include parts that may have undergone atleast some post-production testing of any appropriate type (includingwithout limitation a resonance inspection). Another part class includesin-service parts—parts that have been released from production for usein one or more end-use applications. An “in-service part” in the contextof the embodiments to be addressed herein encompasses a part that hasbeen used to at least some extent after having been released by themanufacturer. An in-service part may be a part that has been put intouse by a party other than the manufacturer (e.g., a customer or enduser). Although an in-service part could be used autonomously orindependently of any other parts, an in-service part may be incorporatedby an assembly or system (e.g., a turbine blade (an in-service part) ina jet engine (an assembly or system)).

The signal generator 102 generates signals that are directed to thetransducer 104 for transmission to the part 120 in any appropriatemanner/fashion (e.g., via physical contact between the transducer 104and the part 120). Signals provided by the signal generator 102 are usedto mechanically excite the part 120 (e.g., to provide energy to the part120 for purposes of inducing vibration). Multiple frequencies may beinput to the part 120 through the transducer 104 in any appropriatemanner. This may be characterized as “sweeping” through a range offrequencies that are each input to the part 120, and this may be done inany appropriate manner for purposes of the resonance inspection tool100. Any appropriate number/range of frequencies may be utilized, andany appropriate way of progressing through a plurality of frequencies(e.g., a frequency range) may be utilized by the resonance inspectiontool 100.

In one embodiment, at least one other transducer 106 is utilized in theresonance inspection of the part 120 using the resonance inspection tool100 of FIG. 3, including where two transducers 106 are utilized (e.g.,in accordance with the embodiment of FIGS. 1 and 2 noted above). Each ofthe transducers 106, as well as the input or drive transducer 104, maybe in physical contact with the part 120. It may be such that the part120 is in fact entirely supported by the transducer 104 and anyadditional transducers 106. Each transducer 106 that is utilized by theresonance inspection tool 100 is used to acquire the frequency responseof the part 120 to the frequencies input to the part 120 by the drivetransducer 104, and therefore each transducer 106 may be characterizedas an output or receiver transducer 106.

Another embodiment of the resonance inspection tool 100 of FIG. 3utilizes only the transducer 104. That is, no additional transducers 106are utilized by the resonance inspection tool 100 in this case, andtherefore the transducer 106 is presented by dashed lines in FIG. 3. Inthis case, the transducer 104 is used to input a drive signal to thepart 120 (e.g., to excite the part 120 at a plurality of differentfrequencies), and is also used to acquire the frequency response of thepart 120 to these input drive frequencies. For instance, a first drivesignal at a first frequency (from the signal generator 102) may betransmitted to the part 120 through the transducer 104, the transmissionof this first drive signal may be terminated, and the transducer 104 maybe used to acquire a first frequency response of the part 120 to thisfirst drive signal (including while a drive signal is being transmittedto the part 120). The signal generator 102 may also be used provide asecond drive signal at a second frequency to the transducer 104, whichin turn transmits the second drive signal to the part 120, thetransmission of this second drive signal may be terminated, and thetransducer 104 may once again be used to acquire a second frequencyresponse of the part 120 to this second drive signal (including while adrive signal is being transmitted to the part 120). This may be repeatedany appropriate number of times and utilizing any appropriate number offrequencies and frequency values. One or more drive signals may besequentially transmitted to the part 120 by the signal generator 102 andtransducer 104, one or more drive signals may be simultaneouslytransmitted to the part 120 by the signal generator 102 and transducer104, or any combination thereof.

The frequency response of the part 120 is transmitted to the computer108 of the resonance inspection tool 100 of FIG. 3. This computer 108may be of any appropriate type and/or configuration, and is used by theresonance inspection tool 100 to evaluate the part 120 in at least somefashion (e.g., to determine whether to accept or reject the part 120).Generally, the part 120 is vibrated by the transducer 104 according to apredetermined signal(s), and the part 120 is evaluated by the resultingvibrational response of the part 120. For instance, this evaluation mayentail assessing the part 120 for one or more defects of various types,assessing whether the part 120 is at or near the end of its useful,life, assessing whether the part 120 is aging normally or abnormally, orany combination thereof.

The computer 108 may incorporate and utilize the above-noted assessmentmodule 110 to evaluate the response of the part 120 to a resonanceinspection. The assessment module 110 may be of any appropriateconfiguration and may be implemented in any appropriate manner. In oneembodiment, the assessment module 110 includes at least one newproduction part sort logic 112 (e.g., logic configured to determinewhether to accept or reject new production parts), at least onein-service part sort logic 114 (e.g., logic configured to determinewhether to accept or reject in-service parts), along with one or moreprocessors 116 of any appropriate type and which may be implemented inany appropriate manner. The assessment of the response of the part 120to the input drive signals may entail comparing the response to alibrary 118 utilized by the resonance inspection tool 100. This library118 may be stored on a computer-readable storage medium of anyappropriate type or types, including without limitation by using one ormore data storage devices of any appropriate type and disposed in anyappropriate arrangement.

The library 118 of the resonance inspection tool 100 may include varioustypes of resonance inspection results to allow the resonance inspectiontool 100 to assess a part 120.

Generally, the resonance inspection results from the part 120 arecompared with data in the library 118 from at least one other part thatis the same as the part 120 in one or more respects (e.g., a part 120 inthe form of a turbine blade will be compared to turbine blade data inthe library 118; a part 120 in the form of a turbine blade will not becompared with ball bearing data in the library 118). Representativeresonance inspection results are presented in FIG. 4, and are of a typethat may be included in the library 118. The three spectra 122 shown inFIG. 4 represent the frequency response of a new production part 120 toa certain input frequency, and where this new production part 120 hasbeen accepted by the resonance inspection tool 100. Note how the threepeaks 128 a, 128 b, and 128 c differ in at least one respect between thevarious spectra 122, but yet the corresponding new production part 120is acceptable in all three instances.

The three spectra 124 shown in FIG. 4 represent the frequency responseof an in-service production part 120 to a certain input frequency, andwhere this in-service part 120 has been accepted by the resonanceinspection tool 100. Note how the three peaks 128 a, 128 b, and 128 c inthe spectra 124 differ in at least one respect from the correspondingpeaks 128 a, 128 b, and 128 c in the spectra 122 (again, associated witha new production part 120).

The three spectra 126 shown in FIG. 4 represent the frequency responseof an in-service production part 120 to a certain input frequency, andwhere this in-service part 120 has been rejected by the resonanceinspection tool 100. Note how the three peaks 128 a, 128 b, and 128 c inthe spectra 126 differ in at least one respect from the correspondingpeaks 128 a, 128 b, and 128 c in the spectra 124 (again, associated withan in-service part 120 that the resonance inspection tool 100 wouldaccept). Generally, each of the peaks 128 a, 128 b, and 128 c in thespectra 126 has shifted to the left compared to the corresponding peaks128 a, 128 b, and 128 c in the spectra 122 and 124. Moreover, note the“compression” between the peaks 128 a, 128 b in the spectra 126 comparedto the spectra 122, 124, as well as the “compression” between the peaks128 b, 128 c in the spectra 126 compared to the spectra 122, 124.

One embodiment of a resonance inspection protocol that may be utilizedby the resonance inspection tool 100 of FIG. 3 is presented in FIG. 5and is identified by reference numeral 130. Step 132 of the resonanceinspection protocol 130 is directed to exciting a part 120 at a drivefrequency (e.g. via a signal from the signal generator 102 that is inputto the part 120 through the transducer 104). The response of the part120 is obtained or measured pursuant to step 134 (e.g., via one or moretransducers 106; via the transducer 104 in a single transducerconfiguration). It should be appreciated that steps 132 and 134 may beexecuted in at least partially overlapping relation (e.g., the frequencyresponse of the part 120 could be obtained as a drive signal is beingapplied to the part 120), although steps 132 and 134 could besequentially executed as well.

The frequency response of the part 120 is assessed pursuant to step 136of the resonance inspection protocol 130. Step 138 of the protocol 130is directed to determining if the frequency sweep is complete—whethereach of the desired drive frequencies has been input to the part 120. Ifnot, the protocol 130 proceeds to step 140, and which is directed toupdating or changing the drive frequency to be input to the part 120.Control is then returned to step 132 for repetition in accordance withthe foregoing. Once the part 120 has been driven at each of the desiredfrequencies, the protocol 130 is terminated pursuant to step 142.

Step 136 of the resonance inspection protocol 130 is again directed toassessing the response (e.g., frequency) of the part 120 (e.g., usingthe sort logic 112 or 114 and/or comparing the response of the part 120to the library 118 of the resonance inspection tool 100). Thisassessment may be undertaken at any appropriate time and in anyappropriate manner. For instance, the assessment associated with step136 could be undertaken while the part 120 continues to be driven by asignal at one or more frequencies. Another option is for the assessmentprovided by step 136 to be undertaken only after all drive signals havebeen input to the part 120 (step 132), after the all frequency responseshave been obtained (step 134), or both.

One embodiment of a sort protocol is presented in FIG. 6 and isidentified by reference numeral 150. The sort protocol 150 may beutilized by the in-service part sort logic 114 of the resonanceinspection tool 100 shown in FIG. 3, and is configured for theassessment of in-service parts. Generally, the sort protocol 150 isdirected to determining whether or not an in-service part isexperiencing normal changes while in service. Stated another way, thesort protocol 130 may be characterized as being directed to determiningwhether an in-service part is aging normally or abnormally and via aresonance inspection. Each resonance inspection of an in-service partmay be conducted while the in-service part remains in an installed stateor condition (e.g., in situ) for purposes of the sort protocol 150.Alternatively, each resonance inspection of an in-service part may beconducted with the in-service part being in an uninstalled state orcondition (e.g., after having been removed from an assemblyincorporating the same) for purposes of the sort protocol 150.

A resonance inspection of a first in-service part (e.g., part 120 shownin FIG. 3) is conducted pursuant to step 152 of the sort protocol 150 ofFIG. 6 (e.g., via execution of the resonance inspection protocol 130 ofFIG. 5). The frequency response of the first in-service part is comparedwith a resonance standard pursuant to step 154. This “resonancestandard” may be incorporated by the library 118 used by the resonanceinspection tool 100 (FIG. 3) and/or may be utilized by the in-servicepart sort logic 114, and in any case may characterize or define whatshould be a “normal change” for a predetermined in-service part (e.g.,to determine whether the first in-service part is changing or aging in anormal manner or fashion). That is, the comparison of step 154 isundertaken for purposes of determining whether the first in-service partis changing normally or abnormally (step 156). If the comparison withthe resonance standard (step 154) determines that the first in-servicepart is changing abnormally, the sort protocol 150 proceeds from step156 to step 160. A first in-service part that is changing abnormally maybe rejected by the sort protocol 150 pursuant to step 160 (e.g., thefirst in-service part may be designated to be taken out of service). Afirst in-service part that is changing normally is accepted by the sortprotocol 150 pursuant to step 158 (e.g., the first in-service part maybe returned to service).

The resonance standard associated with step 154 may include actualand/or projected/predicted resonance inspection results. Moreover, theseresonance inspection results may be from various points in time over thelife cycle of a part (e.g., resonance inspection results when in theform of a new production part, resonance inspection results at orassociated with 5,000 cycles of usage, resonance inspection results ator associated with 10,000 cycles of usage, resonance inspection resultsat or associated with 15,000 cycles of usage, and so forth). Step 156 ofthe sort protocol 150 may or may not take usage data (e.g., hours orcycles of operation) into account when assessing a particular in-servicepart. For instance, step 156 could be configured so that resonanceinspection results from the in-service part being assessed via the sortprotocol 150 would have to “match” data in the resonance standard havingthe same or comparable usage data (e.g., if the in-service part that wasbeing assessed via the sort protocol 150 was at 10,000 cycles of usage,step 156 could be configured such that resonance inspection results fromthis in-service part would have to match data in the resonance standardthat are also associated with 10,000 cycles of usage). Step 156 couldalso be configured so that resonance inspection results from thein-service part being assessed via the sort protocol 150 would only needto “match” data in the resonance standard, regardless of any associatedusage data (e.g., step 156 could be configured to determine that a partat 10,000 cycles was changing normally, even though its resonanceinspection results “matched” data in the resonance standard that was infact associated with 20,000 cycles).

The resonance standard associated with step 154 of the sort protocol 150of FIG. 6 may be of various forms. Representative resonance standardsare shown in FIG. 6. The resonance standard for step 154 may be in theform of: 1) spectra from one or more other in-service parts (e.g.,spectra from a resonance inspection previously conducted on one or morein-service parts other than that being inspected pursuant to the sortprotocol 150 (box 162 a); 2) one or more spectra from a population ofother in-service parts (box 162 b); 3) resonance inspection resultspredicted and/or derived via mathematical modeling (box 162 c); and 4)spectra obtained from accelerated life testing (box 162 d).

The resonance standard associated with step 154 of the sort protocol 150could be in the form of any one or more of the type of spectra 124 shownin FIG. 4 (e.g., box 162 a). If the resonance inspection results fromthe resonance inspection conducted pursuant to step 152 matched orcomplied with any of these spectra 124 in one or more respects, thein-service part could be accepted by step 158 of the sort protocol 150.

The resonance standard used by step 154 of the sort protocol 150 may bebased upon a population of in-service parts (box 162 b). This populationof in-service parts does not need to include the first in-service partthat is being assessed by the sort protocol 150. The population ofin-service parts may be viewed as a “peer group” for purposes ofassessing the first in-service part via the sort protocol 150 (e.g.,other parts manufactured in accordance with common specifications and/orthat are functionally interchangeable with the first in-service part).For instance, the resonance standard may be in the form of spectra(e.g., spectra 124 from FIG. 4) from each of a plurality of in-serviceparts that are within the population. If the comparison of step 154determines that the resonance inspection results from the firstin-service part (step 152) match or comply with any of these spectrafrom the population in one or more respects, the first in-service partmay be accepted pursuant to step 158 of the sort protocol 150. Theresonance standard associated with step 154 may also be in the form ofan average of spectra from each of a plurality of in-service parts thatare within the noted population. If the comparison of step 154determines that the resonance inspection results (step 152) match orcomply with this spectral average from the population in one or morerespects, the first in-service part may be accepted pursuant to step 158of the sort protocol 150.

The resonance standard associated with step 154 of the sort protocol 150may also be provided by mathematical modeling (box 162 c). Thismathematical modeling may be used to 50574-00039 generate resonanceinspection results for various times over the life of a part that ischanging normally. If the comparison of step 154 determines that theresonance inspection results (step 152) match or comply with any ofthese mathematically derived resonance inspection results in one or morerespects, the first in-service part may be accepted pursuant to step 158of the sort protocol 150.

The resonance standard associated with step 154 of the sort protocol 150may also be provided by accelerated life testing (box 162 d). Resonanceinspection results may be acquired as a part undergoes accelerated lifetesting, and these resonance inspection results may be used by theresonance standard associated with step 154. If the comparison of step154 determines that the resonance inspection results (step 152) match orcomply with any of the resonance inspection results acquired during theaccelerated life testing in one or more respects, the first in-servicepart may be accepted pursuant to step 158 of the sort protocol 150.

One embodiment of a sort initialization protocol is presented in FIG. 7and is identified by reference numeral 170. The sort initializationprotocol 170 may be utilized by and/or to configure the in-service partsort logic 114 of the resonance inspection tool 100 shown in FIG. 3, andis thereby associated with the assessment of in-service parts (e.g.,logic configured to determine whether an in-service part should berejected or accepted). A resonance inspection of a plurality ofin-service parts (e.g., part 120 shown in FIG. 3) is conducted pursuantto step 172 of the sort initialization protocol 170 of FIG. 7 (e.g., viaexecution of the resonance inspection protocol 130 of FIG. 5). A firstsubset of “normal” in-service parts (that underwent resonance inspectionpursuant to step 172) is defined pursuant to step 174. A determinationas to whether or not a given in-service part from step 172 is “normal”for purposes of step 174 may be undertaken in any appropriate manner,for instance using destructive testing, nondestructive testing, and/or acombination thereof.

A second subset of “abnormal” in-service parts (that underwent resonanceinspection pursuant to step 172) is defined pursuant to step 176 of thesort initialization protocol 170. A determination as to whether or not agiven in-service part from step 172 is “abnormal” for purposes of step176 may be undertaken in any appropriate manner, for instance usingdestructive testing, nondestructive testing, or a combination thereof.In one embodiment, an in-service part that undergoes a resonanceinspection pursuant to step 172 is characterized as normal (step 174) orabnormal (step 176) other than by the results of the resonanceinspection associated with step 172 (e.g., via DT and/or NDT).

One or more destructive testing techniques may be used, one or morenondestructive testing techniques may be used, or both, in relation toeach of steps 174 and 176 of the sort initialization protocol 170 ofFIG. 7. Representative nondestructive testing techniques that may beused in relation to each of steps 174 and 176 includes withoutlimitation visual inspection, microscopy, magnetic particle, penetrant,eddy current, x-ray, computed tomography, flash thermography,ultrasound, sonic infra-red, phased array, or the like. Representativedestructive testing techniques that may be used in relation to each ofsteps 174 and 176 includes without limitation fatigue testing, statictesting, thermal testing, metalography, sectioning, ablation, chemicalreduction, or the like.

Step 178 of the sort initialization protocol 170 of FIG. 7 is directedto defining a normal standard, while step 180 of the protocol 170 isdirected to defining an abnormal standard. The normal standardassociated with step 178 may be defined by one or more of the in-serviceparts associated with step 174 and may utilize results of thecorresponding resonance inspection from step 172 (e.g., spectra of eachin-service part within the first subset could be used by the normalstandard; an average spectra from a plurality of in-service parts withinthe first subset could be used by the normal standard). Similarly, theabnormal standard associated with step 180 may be defined by one or moreof the in-service parts associated with step 176 and may utilize resultsof the corresponding resonance inspection from step 172 (e.g., spectraof each in-service part within the second subset could be used by theabnormal standard; an average spectra from a plurality of in-serviceparts within the second subset could be used by the abnormal standard).Both the normal standard (178) and the abnormal standard (step 180) maybe stored (e.g., on a computer-readable storage medium) for use by theresonance inspection tool 100 through execution of step 182 of the sortinitialization protocol 170 (e.g., included in the library 118 shown inFIG. 3).

Another embodiment of a sort protocol is presented in FIG. 8 and isidentified by reference numeral 190. The sort protocol 190 may beutilized by the in-service part sort logic 114 of the resonanceinspection tool 100 shown in FIG. 3, and is configured for theassessment of in-service parts. The resonance inspection of anin-service part may be conducted while the in-service part remains in aninstalled state or condition (e.g., in situ) for purposes of the sortprotocol 190. Alternatively, the resonance inspection of an in-servicepart may be conducted with the in-service part being in an uninstalledstate or condition (e.g., after having been removed from an assemblyincorporating the same) for purposes of the sort protocol 190.

A resonance inspection of a first in-service part (e.g., part 120 shownin FIG. 3) is conducted pursuant to step 192 of the sort protocol 190 ofFIG. 8 (e.g., via execution of the resonance inspection protocol 130 ofFIG. 5). Results of the resonance inspection from step 192 may becompared with an abnormal standard (step 194). The abnormal standardassociated with steps 194 and 196 may be provided by the sortinitialization protocol 170 of FIG. 7. In any case, step 196 of the sortprotocol 190 is directed to determining if resonance inspection results(step 192) comply with the abnormal standard. The first in-service partis rejected if the resonance inspection results (step 192) do in factcomply with the abnormal standard (step 198).

Results of the resonance inspection may be compared with a normalstandard (step 200). Step 202 is directed to determining if resonanceinspection results (step 192) comply with the normal standard. Thenormal standard associated with steps 200 and 202 may be provided by thesort initialization protocol 170 of FIG. 7. In any case, the firstin-service part is accepted if resonance inspection results (step 192)do in fact comply with the normal standard (step 204). The firstin-service part is rejected if resonance inspection results (step 192)do not comply with the normal standard (step 206) in the illustratedembodiment.

The protocol 190 may be configured to execute steps 194 and 200 in anorder different from that shown in FIG. 8. Consider the case where theprotocol 190 is configured to execute step 200 (comparison with a normalstandard) before step 194 (comparison with an abnormal standard). Ifthrough execution of step 202 a determination is made that resonanceinspection results (step 192) do in fact comply with the normalstandard, steps 194 and 196 could then be executed. If through executionof step 196 a determination is made that resonance inspection results(step 192) do not comply with the abnormal standard, the protocol 190could then proceed to the execution of step 204 (where the firstin-service part is accepted by the resonance inspection tool 100).However, if a determination was made that the resonance inspectionresults (step 192) comply with the abnormal standard pursuant to step196, steps 202 and 196 of the protocol 190 would be providinginconsistent results. In this case, the sort protocol 190 could beconfigured to reject the first in-service part (step 198)—even throughresonance inspection results of the first in-service part weredetermined by the resonance inspection tool 100 to comply with thenormal standard (step 202).

The sort protocol 190 could also be configured to address a conditionwhen resonance inspection results from step 194 do no match either thenormal standard (step 200) or the abnormal standard (step 196). Oneoption would be to associate the first in-service part with an unknowncondition, and to thereafter further assess the first in-service part.The results of this further analysis could be used to update either theabnormal standard or the normal standard, depending upon whether thefirst in-service part was determined to be normal or abnormal.

One embodiment of a new production part sort update protocol ispresented in FIG. 9 and is identified by reference numeral 210. The sortupdate protocol 210 may be utilized by the new production part sortlogic 112 of the resonance inspection tool 100 shown in FIG. 3.Generally, the sort update protocol 210 of FIG. 9 is configured toassess one or more in-service parts, and utilizes this assessment forpurposes of updating the new production part sort logic 112 of theresonance inspection tool 100. The resonance inspection of an in-servicepart may be conducted while the in-service part remains in an installedstate or condition (e.g., in situ) for purposes of the sort updateprotocol 210. Alternatively, the resonance inspection of an in-servicepart may be conducted with the in-service part being in an uninstalledstate or condition (e.g., after having been removed from an assemblyincorporating the same) for purposes of the sort update protocol 210.

A resonance inspection of a first in-service part (e.g., part 120 shownin FIG. 3) is conducted pursuant to step 212 of the sort update protocol210 of FIG. 9 (e.g., via execution of the resonance inspection protocol130 of FIG. 5). The first in-service part is assessed for anymanufacturing defects pursuant to step 214 of the sort update protocol210. Any appropriate technique or combination of techniques may be usedto determine whether or not the first in-service part has one or moremanufacturing defects (e.g., via destructive testing and/ornondestructive testing). If no manufacturing defects are identified inthe first in-service part, the sort update protocol proceeds from step216 to step 218, which terminates the protocol 210. However, if at leastone manufacturing defect is identified in the first in-service part(through execution of step 214), the sort update protocol 210 proceedsfrom step 216 to step 220. Pursuant to step 220, data from the resonanceinspection (step 212) that corresponds with a given manufacturing defectis selected. This may be done in relation to each manufacturing defectthat is identified in the first in-service part through execution ofstep 214. The data from the resonance inspection that corresponds with amanufacturing defect may then be used to update the new production partsort logic 112 for the resonance inspection tool 100 of FIG. 3. Forinstance, the library 118 of the resonance inspection tool 100 may beupdated such that new production parts that originally would have beenaccepted by the resonance inspection tool 100 (prior to execution of thesort update protocol 210) will now be rejected by the resonanceinspection tool 100 if any such new production part includes amanufacturing defect that has been identified through execution of thesort update protocol 210 of FIG. 9.

Another embodiment of a sort protocol is presented in FIG. 10 and isidentified by reference numeral 230. The sort protocol 230 may beutilized by the in-service part sort logic 114 of the resonanceinspection tool 100 shown in FIG. 3, and is configured for theassessment of in-service parts. The resonance inspection of anin-service part may be conducted while the in-service part remains in aninstalled state or condition (e.g., in situ) for purposes of the sortprotocol 230. Alternatively, the resonance inspection of an in-servicepart may be conducted with the in-service part being in an uninstalledstate or condition (e.g., after having been removed from an assemblyincorporating the same) for purposes of the sort protocol 230.

The sort protocol 230 is generally directed to monitoring in-serviceparts for an end-of-life (“EOL”) state or condition based upon resonanceinspections of the in-service part that are conducted over time.Spaced-in-time resonance inspections of an in-service part may beconducted on any appropriate basis. For instance, an in-service partcould be scheduled for a resonance inspection based upon time (e.g., ona calendar quarterly basis), based upon usage/usage data (e.g., hours ofoperation; cycles of operation), or the like. In one embodiment, anin-service part is scheduled for a resonance inspection based upon whatmay be characterized as a “cycle target.” Such a “cycle target” could bein the form of the in-service part being within a range of cycles,having been used for a minimum number of cycles, or the like.

A resonance inspection of a first in-service part (e.g., part 120 shownin FIG. 3) is conducted pursuant to step 232 of the sort protocol 230 ofFIG. 10 (e.g., via execution of the resonance inspection protocol 130 ofFIG. 5). Resonance inspection data (e.g., the frequency response of thefirst in-service part) is acquired pursuant to step 234. The acquisitionof resonance inspection data from step 234 may be characterized as beingpart of the resonance inspection associated with step 232.

Step 236 of the sort protocol 230 is directed to the monitoring firstresonance inspection data. More specifically, step 236 is directed tomonitoring first resonance inspection data for an occurrence of a firstcondition. This “first condition” may be in the form of a certaintime-rate-of-change in the first resonance inspection data, and will bediscussed in more detail below. In the event the first resonanceinspection data does not exhibit a first condition, the sort protocol230 proceeds from step 238 to step 240. As the first condition was notidentified in the first resonance inspection data, step 240 is directedto accepting the first in-service part. For instance, the protocol 230may designate the first in-service part as being appropriate for furtherservice. Another resonance inspection of the first in-service part maybe conducted at a later time (e.g., after the expiration of a designatednumber of hours of operation or cycles of operation). As such, step 240may return control to step 232 of the sort protocol 230 for repetitionin accordance with the foregoing. Since a subsequent resonanceinspection will typically be conducted at a later point in time, step240 could also terminate the protocol 230 (e.g., an “end” step, and suchthat the protocol 230 would be re-run for each resonance inspection ofthe first in-service part).

In the event the sort protocol 230 identifies an occurrence of a firstcondition (e.g., via steps 236 and/or 238), the protocol 230 proceedsfrom step 238 to step 242. Step 242 is directed to associating an“end-of-life” or EOL condition or state with the first in-service part.This may entail designating the first in-service part for retirementsuch that the first in-service part is not returned to service.

The first resonance inspection data (step 236) may be characterized asbeing part of and/or embodied by the resonance inspection data (step234). In one embodiment, the first resonance inspection data (step 236)may be only part and/or may relate to only part of the resonanceinspection data (step 234). The first resonance inspection data (step236) may also be characterized as being based upon and/or derived fromthe resonance inspection data (step 234).

The first resonance inspection data (step 236) may be in the form of afrequency shift in the resonance inspection data (step 234) over time.The first resonance inspection data (step 236) may be in the form of: 1)a relative shift of at least one peak in the resonance inspection dataacquired from multiple resonance inspections of the first in-servicepart (e.g., a shift of a first peak in the resonance inspection datarelative to a second peak in the resonance inspection data); 2) anabsolute shift of at least one peak in the resonance inspection dataacquired from multiple resonance inspections of the first in-servicepart (e.g., a shift of a first peak in the resonance inspection data);3) an appearance of at least one peak in the resonance inspection dataacquired from multiple resonance inspections of the first in-servicepart; and 4) a disappearance of at least one peak in the resonanceinspection data acquired from multiple resonance inspections of thefirst in-service part.

The “first condition” associated with step 238 may be characterized asbeing directed to a time-rate-of-change in resonance inspection resultsfrom resonance inspection to resonance inspection. That is, one or moreparameters embodied by and/or relating to the resonance inspectionresults may be monitored from resonance inspection to resonanceinspection to assess any corresponding change that may be occurring inrelation to any such parameter. A certain change in any such parametermay be characterized as an occurrence of the first condition (step 238).

FIG. 11 illustrates representative first resonance inspection data thatmay be utilized by the sort protocol 230 of FIG. 10. Plot 250 may be inthe form of a frequency shift of a certain peak in the resonanceinspection results from resonance inspection to resonance inspection(the “diamonds” being data points obtained from different resonanceinspections over time). Plot 252 may be in the form of an “elongation”between a pair of peaks in the resonance inspection results fromresonance inspection to resonance inspection (the “triangles” being datapoints obtained from different resonance inspections over time).“Elongation” means that the spacing between a pair of peaks in theresonance inspection results is being monitored for increases.

The foregoing description of the present invention has been presentedfor purposes of illustration and description. Furthermore, thedescription is not intended to limit the invention to the form disclosedherein. Consequently, variations and modifications commensurate with theabove teachings, and skill and knowledge of the relevant art, are withinthe scope of the present invention. The embodiments describedhereinabove are further intended to explain best modes known ofpracticing the invention and to enable others skilled in the art toutilize the invention in such, or other embodiments and with variousmodifications required by the particular application(s) or use(s) of thepresent invention. It is intended that the appended claims be construedto include alternative embodiments to the extent permitted by the priorart.

1. A method of evaluating in-service parts, wherein a resonanceinspection comprises exciting a part at a plurality of input frequenciesand obtaining a frequency response of the part at said plurality ofinput frequencies, wherein an in-service part is a part that has beenreleased from production and used by an end user, wherein said methodcomprises the steps of: performing said resonance inspection on a firstin-service part; comparing said frequency response from said resonanceinspection of said first in-service part with a resonance standard,wherein said resonance standard defines what should be a normal changingof said first in-service part while in service, wherein said resonancestandard is based upon at least one other in-service part thatcorresponds with said first in-service part, and determining whethersaid first in-service part is changing abnormally, wherein saiddetermining step comprises said comparing step.
 2. The method of claim1, wherein said resonance inspection of said first in-service partcomprises using at least one transducer that excites said firstin-service part through a range of frequencies and using at least twoother transducers to measure said frequency response of said firstin-service part.
 3. The method of claim 1, wherein said resonanceinspection of said first in-service part comprises using a firsttransducer that excites said first in-service part at each of multiplefrequencies, and also using said first transducer to measure saidfrequency response of said first in-service part.
 4. The method of claim1, wherein said resonance inspection of said first in-service part isperformed with said first in-service part being in an installedcondition.
 5. The method of claim 1, wherein said resonance inspectionof said first in-service part is performed with said first in-servicepart being in an uninstalled condition.
 6. The method of claim 1,wherein said resonance standard is stored on a computer-readable storagemedium, and wherein said comparing and determining steps each compriseusing at least one processor.
 7. The method of claim 1, wherein saidresonance standard comprises spectra of at least one other in-servicepart.
 8. The method of claim 1, wherein said resonance standard is basedupon resonance inspection data from a population of a plurality ofin-service parts.
 9. The method of claim 8, wherein said resonancestandard comprises representative spectra in the form of an average ofspectra from each of said plurality of in-service parts that define saidpopulation.
 10. The method of claim 8, wherein a first assembly isdefined by first specifications, and wherein each of plurality ofin-service parts that define said population and said first in-servicepart are incorporated by at least one said first assembly in accordancewith said first specifications.
 11. The method of claim 8, wherein eachof said plurality of in-service parts and said first in-service part aredefined by common specifications.
 12. The method of claim 1, furthercomprising the steps of: manufacturing a plurality of first parts;putting into service each of said plurality of first parts, wherein saidplurality of first parts comprises said first in-service part; andperforming said resonance inspection on each of said plurality of firstparts once each of said plurality of first parts has been in service fora certain duration, wherein said resonance standard comprises results ofsaid resonance inspection of a plurality of said first parts other thansaid first in-service part.
 13. The method of claim 12, furthercomprising the step of: comparing results of said resonance inspectionof said first in-service part with results of at least one prior-in-timesaid resonance inspection of said first in-service part.
 14. The methodof claim 1, wherein said resonance standard comprises results from aplurality of spaced-in-time said resonance inspections previouslyperformed on another in-service part that corresponds with said firstin-service part.
 15. The method of claim 14, wherein said anotherin-service part is incorporated by a fleet leader.
 16. The method ofclaim 1, wherein said resonance standard comprises a mathematical modelof how said first in-service part should change over time while inservice.
 17. The method of claim 1, wherein said resonance standardcomprises results from accelerated life testing of at least one partthat corresponds with said first in-service part. 18.-59. (canceled)